From 804cd9f75fc8f9a905c832fcc39de68d7c969356 Mon Sep 17 00:00:00 2001
From: Gregory Sanders <gsanders87@gmail.com>
Date: Fri, 31 May 2019 12:39:55 -0400
Subject: [PATCH] Update PAK internals, helper functions

---
 src/primitives/pak.cpp | 126 +++++++++++++++++++----------------------
 src/primitives/pak.h   |  39 +++++--------
 src/rpc/misc.cpp       |  18 ++----
 src/validation.cpp     |  77 -------------------------
 src/validation.h       |   3 -
 5 files changed, 76 insertions(+), 187 deletions(-)

diff --git a/src/primitives/pak.cpp b/src/primitives/pak.cpp
index 430e26ccc1..997fd0cd70 100644
--- a/src/primitives/pak.cpp
+++ b/src/primitives/pak.cpp
@@ -4,6 +4,7 @@
 
 #include <primitives/pak.h>
 #include <pubkey.h>
+#include <dynafed.h>
 
 // ELEMENTS
 
@@ -33,73 +34,9 @@ public:
 static CSecp256k1Init instance_of_csecp256k1;
 }
 
-CScript CPAKList::Magic()
-{
-    CScript scriptPubKey;
-    scriptPubKey.resize(6);
-    scriptPubKey[0] = OP_RETURN;
-    scriptPubKey[1] = 0x04;
-    scriptPubKey[2] = 0xab;
-    scriptPubKey[3] = 0x22;
-    scriptPubKey[4] = 0xaa;
-    scriptPubKey[5] = 0xee;
-    return scriptPubKey;
-}
-
-std::vector<CScript> CPAKList::GenerateCoinbasePAKCommitments() const
-{
-    std::vector<CScript> commitments;
-    CScript scriptPubKey = CPAKList::Magic();
-
-    for (unsigned int i = 0; i < m_offline_keys.size(); i++) {
-        CScript scriptCommitment(scriptPubKey);
-        unsigned char pubkey[33];
-        size_t outputlen = 33;
-        secp256k1_ec_pubkey_serialize(secp256k1_ctx_pak, pubkey, &outputlen, &m_offline_keys[i], SECP256K1_EC_COMPRESSED);
-        assert(outputlen == 33);
-        scriptCommitment << std::vector<unsigned char>(pubkey, pubkey+outputlen);
-        secp256k1_ec_pubkey_serialize(secp256k1_ctx_pak, pubkey, &outputlen, &m_online_keys[i], SECP256K1_EC_COMPRESSED);
-        assert(outputlen == 33);
-        scriptCommitment << std::vector<unsigned char>(pubkey, pubkey+outputlen);
-        commitments.push_back(scriptCommitment);
-    }
-
-    return commitments;
-}
-
-std::vector<CScript> CPAKList::GenerateCoinbasePAKReject() const
-{
-    CScript scriptPubKey = CPAKList::Magic();
-
-    std::vector<unsigned char> reject;
-    reject.push_back('R');
-    reject.push_back('E');
-    reject.push_back('J');
-    reject.push_back('E');
-    reject.push_back('C');
-    reject.push_back('T');
-
-    scriptPubKey << reject;
-
-    std::vector<CScript> commitment;
-    commitment.push_back(scriptPubKey);
-    return commitment;
-}
-
-void CPAKList::CreateCommitments(std::vector<CScript> &commitments) const
-{
-    if(reject) {
-        commitments = GenerateCoinbasePAKReject();
-    } else {
-        commitments = GenerateCoinbasePAKCommitments();
-    }
-}
-
 bool CPAKList::operator==(const CPAKList &other) const
 {
-    if (this->reject != other.reject) {
-        return false;
-    } else if (this->m_offline_keys.size() != other.m_offline_keys.size()) {
+    if (this->m_offline_keys.size() != other.m_offline_keys.size()) {
         return false;
     } else {
         for (unsigned int i = 0; i < this->m_offline_keys.size(); i++) {
@@ -112,7 +49,7 @@ bool CPAKList::operator==(const CPAKList &other) const
     return true;
 }
 
-bool CPAKList::FromBytes(CPAKList &paklist, std::vector<std::vector<unsigned char> >& offline_keys_bytes, std::vector<std::vector<unsigned char> >& online_keys_bytes, bool is_reject)
+bool CPAKList::FromBytes(CPAKList &paklist, const std::vector<std::vector<unsigned char> >& offline_keys_bytes, const std::vector<std::vector<unsigned char> >& online_keys_bytes)
 {
     if(offline_keys_bytes.size() != online_keys_bytes.size()
         || offline_keys_bytes.size() > SECP256K1_WHITELIST_MAX_N_KEYS) {
@@ -134,11 +71,11 @@ bool CPAKList::FromBytes(CPAKList &paklist, std::vector<std::vector<unsigned cha
         online_keys.push_back(pubkey2);
     }
 
-    paklist = CPAKList(offline_keys, online_keys, is_reject);
+    paklist = CPAKList(offline_keys, online_keys);
     return true;
 }
 
-void CPAKList::ToBytes(std::vector<std::vector<unsigned char> >& offline_keys, std::vector<std::vector<unsigned char> >& online_keys, bool &is_reject) const
+void CPAKList::ToBytes(std::vector<std::vector<unsigned char> >& offline_keys, std::vector<std::vector<unsigned char> >& online_keys) const
 {
     offline_keys.resize(0);
     online_keys.resize(0);
@@ -151,7 +88,6 @@ void CPAKList::ToBytes(std::vector<std::vector<unsigned char> >& offline_keys, s
         secp256k1_ec_pubkey_serialize(secp256k1_ctx_pak, pubkey, &outputlen, &m_online_keys[i], SECP256K1_EC_COMPRESSED);
         online_keys.push_back(std::vector<unsigned char>(pubkey, pubkey+outputlen));
     }
-    is_reject = reject;
 }
 
 // Proof follows the OP_RETURN <genesis_block_hash> <destination_scriptpubkey>
@@ -243,3 +179,55 @@ bool ScriptHasValidPAKProof(const CScript& script, const uint256& genesis_hash)
 
     return true;
 }
+
+CPAKList CreatePAKListFromExtensionSpace(const std::vector<std::vector<unsigned char>>& extension_space)
+{
+    std::vector<std::vector<unsigned char>> offline_keys;
+    std::vector<std::vector<unsigned char>> online_keys;
+    for (const auto& entry : extension_space) {
+        // As soon as we find something that is possibly not 2 serialized pubkeys
+        // we stop looking. CPAKList::FromBytes does pubkey validation itself.
+        if (entry.size() != 66) {
+            break;
+        }
+        offline_keys.emplace_back(entry.begin(), entry.begin()+33);
+        online_keys.emplace_back(entry.begin()+33, entry.end());
+        // Allow additional data, just ignore
+        if (offline_keys.size() == SECP256K1_WHITELIST_MAX_N_KEYS) {
+            break;
+        }
+    }
+    CPAKList paklist;
+    if (!CPAKList::FromBytes(paklist, offline_keys, online_keys)) {
+        return CPAKList();
+    }
+    return paklist;
+}
+
+CPAKList GetActivePAKList(const CBlockIndex* pblockindex, const Consensus::Params& params)
+{
+    assert(pblockindex);
+
+    return CreatePAKListFromExtensionSpace(ComputeNextBlockFullCurrentParameters(pblockindex, params).m_extension_space);
+}
+
+bool IsPAKValidOutput(const CTxOut& txout, const CPAKList& paklist)
+{
+    const CChainParams& params = Params();
+    if (txout.scriptPubKey.IsPegoutScript(params.ParentGenesisBlockHash()) &&
+                txout.nAsset.IsExplicit() && txout.nAsset.GetAsset() == params.GetConsensus().pegged_asset &&
+                (!ScriptHasValidPAKProof(txout.scriptPubKey, params.ParentGenesisBlockHash(), paklist))) {
+            return false;
+    }
+    return true;
+}
+
+bool IsPAKValidTx(const CTransaction& tx, const CPAKList& paklist)
+{
+    for (const auto& txout : tx.vout) {
+        if (!IsPAKValidOutput(txout, paklist)) {
+            return false;
+        }
+    }
+    return true;
+}
diff --git a/src/primitives/pak.h b/src/primitives/pak.h
index 3191e4790c..35add8ee26 100644
--- a/src/primitives/pak.h
+++ b/src/primitives/pak.h
@@ -8,28 +8,22 @@
 #include <script/script.h>
 #include <secp256k1/include/secp256k1_whitelist.h>
 #include <boost/optional.hpp>
+#include <chain.h>
 
 class CPAKList
 {
 private:
     std::vector<secp256k1_pubkey> m_offline_keys;
     std::vector<secp256k1_pubkey> m_online_keys;
-    bool reject;
-
-    std::vector<CScript> GenerateCoinbasePAKCommitments() const;
-    std::vector<CScript> GenerateCoinbasePAKReject() const;
 
 public:
-    CPAKList()
-    {
-        reject = true;
-    }
+    CPAKList() {}
     /**
      * Creates a new CPAKList. Requires that the number of offline keys is the same as the number of online keys
      * and that this number is not larger than SECP256K1_WHITELIST_MAX_N_KEYS.
      */
-    CPAKList(std::vector<secp256k1_pubkey> offline_keys, std::vector<secp256k1_pubkey> online_keys, bool reject) :
-        m_offline_keys(offline_keys), m_online_keys(online_keys), reject(reject) {
+    CPAKList(std::vector<secp256k1_pubkey> offline_keys, std::vector<secp256k1_pubkey> online_keys) :
+        m_offline_keys(offline_keys), m_online_keys(online_keys) {
             assert(m_offline_keys.size() == m_online_keys.size());
             assert(m_offline_keys.size() <= SECP256K1_WHITELIST_MAX_N_KEYS);
        }
@@ -41,11 +35,7 @@ public:
     }
     bool IsReject() const
     {
-        return reject;
-    }
-    bool IsEmpty() const
-    {
-        return !reject && this->size() == 0;
+        return size()==0;
     }
     std::vector<secp256k1_pubkey> OnlineKeys() const
     {
@@ -60,24 +50,21 @@ public:
         return m_offline_keys.size();
     }
 
-    static CScript Magic();
-    /** Produce a list of scripts to add to the coinbase to signal changes in PAK list or rejection of any pak proofs to nodes */
-    void CreateCommitments(std::vector<CScript> &commitments) const;
-
-    static bool FromBytes(CPAKList &paklist, std::vector<std::vector<unsigned char> >& offline_keys, std::vector<std::vector<unsigned char> >& online_keys, bool is_reject);
-    void ToBytes(std::vector<std::vector<unsigned char> >& offline_keys, std::vector<std::vector<unsigned char> >& online_keys, bool &is_reject) const;
+    static bool FromBytes(CPAKList &paklist, const std::vector<std::vector<unsigned char> >& offline_keys, const std::vector<std::vector<unsigned char> >& online_keys);
+    void ToBytes(std::vector<std::vector<unsigned char> >& offline_keys, std::vector<std::vector<unsigned char> >& online_keys) const;
 };
 
 /**
  ** Returns true if the script includes valid pegout proof
- ** given the PAK list loaded. Two pushes after regular pegout script:
+ ** given the PAK list. Two pushes after regular pegout script:
  ** <full_pubkey> <proof>
  **/
 bool ScriptHasValidPAKProof(const CScript& script, const uint256& genesis_hash);
 
-// ELEMENTS:
-extern boost::optional<CPAKList> g_paklist_config;
-extern CPAKList g_paklist_blockchain;
-///////////
+CPAKList GetActivePAKList(const CBlockIndex* pblockindex, const Consensus::Params& params);
+
+bool IsPAKValidOutput(const CTxOut& txout, const CPAKList& paklist);
+
+bool IsPAKValidTx(const CTransaction& tx, const CPAKList& paklist);
 
 #endif // BITCOIN_PRIMITIVES_PAK_H
diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index 0e9a5694b0..5717dda169 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -667,8 +667,7 @@ UniValue FormatPAKList(CPAKList &paklist) {
     UniValue paklist_value(UniValue::VOBJ);
     std::vector<std::vector<unsigned char> > offline_keys;
     std::vector<std::vector<unsigned char> > online_keys;
-    bool is_reject;
-    paklist.ToBytes(offline_keys, online_keys, is_reject);
+    paklist.ToBytes(offline_keys, online_keys);
 
     UniValue retOnline(UniValue::VARR);
     UniValue retOffline(UniValue::VARR);
@@ -679,7 +678,7 @@ UniValue FormatPAKList(CPAKList &paklist) {
     }
     paklist_value.pushKV("online", retOnline);
     paklist_value.pushKV("offline", retOffline);
-    paklist_value.pushKV("reject", is_reject);
+    paklist_value.pushKV("reject", retOffline.empty());
     return paklist_value;
 }
 
@@ -688,12 +687,11 @@ UniValue getpakinfo(const JSONRPCRequest& request)
     if (request.fHelp || request.params.size() != 0)
         throw std::runtime_error(
             RPCHelpMan{"getpakinfo",
-                "\nReturns relevant pegout authorization key (PAK) information about this node, both from command line arguments and blockchain data.\n",
+                "\nReturns relevant pegout authorization key (PAK) information about this node, both from blockchain data.\n",
                 {},
                 RPCResult{
             "{\n"
-                "\"config_paklist\"          (array) The PAK list loaded from beta.conf at startup\n"
-                "\"block_paklist\"           (array) The PAK list loaded from latest block commitment\n"
+                "\"block_paklist\"           (array) The PAK list loaded from latest epoch\n"
             "}\n"
                 },
                 RPCExamples{""},
@@ -701,13 +699,9 @@ UniValue getpakinfo(const JSONRPCRequest& request)
 
     LOCK(cs_main);
 
-    UniValue paklist_value(UniValue::VOBJ);
-    if (g_paklist_config) {
-        paklist_value = FormatPAKList(*g_paklist_config);
-    }
     UniValue ret(UniValue::VOBJ);
-    ret.pushKV("config_paklist", paklist_value);
-    ret.pushKV("block_paklist", FormatPAKList(g_paklist_blockchain));
+    CPAKList paklist = GetActivePAKList(chainActive.Tip(), Params().GetConsensus());
+    ret.pushKV("block_paklist", FormatPAKList(paklist));
 
     return ret;
 }
diff --git a/src/validation.cpp b/src/validation.cpp
index e7602a7f39..d809e2f212 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -2628,17 +2628,6 @@ bool CChainState::ConnectTip(CValidationState& state, const CChainParams& chainp
     if (!FlushStateToDisk(chainparams, state, FlushStateMode::IF_NEEDED))
         return false;
 
-    // Get PAK commitment from coinbase, if it exists
-    boost::optional<CPAKList> paklist = GetPAKKeysFromCommitment(*blockConnecting.vtx[0]);
-    if (paklist) {
-        std::vector<std::vector<unsigned char> > offline_keys;
-        std::vector<std::vector<unsigned char> > online_keys;
-        bool is_reject;
-        paklist->ToBytes(offline_keys, online_keys, is_reject);
-        pblocktree->WritePAKList(offline_keys, online_keys, is_reject);
-        g_paklist_blockchain = *paklist;
-    }
-
     int64_t nTime5 = GetTimeMicros(); nTimeChainState += nTime5 - nTime4;
     LogPrint(BCLog::BENCH, "  - Writing chainstate: %.2fms [%.2fs (%.2fms/blk)]\n", (nTime5 - nTime4) * MILLI, nTimeChainState * MICRO, nTimeChainState * MILLI / nBlocksTotal);
     // Remove conflicting transactions from the mempool.;
@@ -3448,72 +3437,6 @@ std::vector<unsigned char> GenerateCoinbaseCommitment(CBlock& block, const CBloc
 }
 
 // ELEMENTS
-boost::optional<CPAKList> GetPAKKeysFromCommitment(const CTransaction& coinbase)
-{
-    std::vector<std::vector<unsigned char> > offline_keys;
-    std::vector<std::vector<unsigned char> > online_keys;
-    bool is_reject = false;
-    for (unsigned int i = 0; i < coinbase.vout.size(); i++) {
-        const CScript& scriptPubKey = coinbase.vout[i].scriptPubKey;
-
-        // OP + push + 4 bytes + push + 33 bytes + push + 33 bytes
-        // or
-        // OP + push + 4 bytes + push + 6 bytes (REJECT)
-
-        CScript::const_iterator pc = scriptPubKey.begin();
-        std::vector<unsigned char> data;
-        opcodetype opcode;
-
-        if (!scriptPubKey.GetOp(pc, opcode, data) || opcode != OP_RETURN){
-            continue;
-        }
-
-        if (!scriptPubKey.GetOp(pc, opcode, data) || data.size() != 4 ||
-                data[0] != 0xab || data[1] != 0x22 || data[2] != 0xaa || data[3] != 0xee) {
-            continue;
-        }
-
-        if (!scriptPubKey.GetOp(pc, opcode, data)){
-            continue;
-        }
-
-        // Check for pak list reject signal
-        // Returns an empty list regardless of other commitments
-        if (data.size() == 6 && data[0] == 'R' && data[1] == 'E' && data[2] == 'J' && data[3] == 'E' && data[4] == 'C' && data[5] == 'T') {
-            is_reject = true;
-            continue;
-        }
-
-        // Check for offline key
-        if (data.size() != 33) {
-            continue;
-        }
-
-        // Check for online key
-        std::vector<unsigned char> data_online;
-        if (!scriptPubKey.GetOp(pc, opcode, data_online) || data_online.size() != 33) {
-            continue;
-        }
-
-        offline_keys.push_back(data);
-        online_keys.push_back(data_online);
-    }
-    if (is_reject) {
-        offline_keys.clear();
-        online_keys.clear();
-    }
-    if (!is_reject && offline_keys.size() == 0) {
-        return boost::none;
-    }
-    CPAKList paklist;
-    if (!CPAKList::FromBytes(paklist, offline_keys, online_keys, is_reject)) {
-        return boost::none;
-    } else {
-        return paklist;
-    }
-}
-
-
 
 
 /** Context-dependent validity checks.
diff --git a/src/validation.h b/src/validation.h
index 2c89fd8299..553b2a449a 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -33,7 +33,6 @@
 
 #include <atomic>
 
-#include <boost/optional.hpp> // GetPAKKeysFromCommitment
 #include <primitives/pak.h> // CPAKList
 
 class CBlockIndex;
@@ -423,8 +422,6 @@ void UpdateUncommittedBlockStructures(CBlock& block, const CBlockIndex* pindexPr
 std::vector<unsigned char> GenerateCoinbaseCommitment(CBlock& block, const CBlockIndex* pindexPrev, const Consensus::Params& consensusParams);
 
 // ELEMENTS
-/** Extract pak commitment from coinbase, if it exists. List must be ordered, but not necessarily consecutive in output index */
-boost::optional<CPAKList> GetPAKKeysFromCommitment(const CTransaction& coinbase);
 
 /** RAII wrapper for VerifyDB: Verify consistency of the block and coin databases */
 class CVerifyDB {